The present invention relates to a new thin cover sheet for use in microscopic staining methods and to a new process for its production.
Glass microscope slides coated with dyestuff for staining biological samples which are to be identified and evaluated under a microscope have been described for a long time. However, the production of correspondingly coated thin cover sheets made of organic material has proved to be difficult. Yet, such sheets are attractive for various reasons; for example from price considerations (less expensive raw materials and possibilities for simpler and continuous production).
Several problems were encountered. The viscosity of the solutions, in water or organic solvents, of the dyestuffs to be applied were frequently too low; therefore, in order to obtain usable stainings, the application of the solution had to be repeated so often that the original price advantages were virtually eliminated. Frequently, poor or incomplete wetting of the thin sheet occurred and resulted in a non-uniform coating of the thin sheet and thus in unusable stainings. The addition of emulsifiers also did not always result in success. Readily soluble dyestuffs were flushed to the edges when the thin film was placed on the moistened microscope slide and were then deficient in the middle when staining was carried out.